The application of rice-bran catalysts containing biopromoters, from rice bran, in the production of synthetic oil was investigated. Trace minerals such as K, Mg, and Mn from rice bran were successfully incorporated into Fe@C microspherical cores and played a cooperative promotional role on the iron species. The yield of the hydrocarbons was strikingly higher than that obtained with the unpromoted catalyst. Further, rice bran is a natural carbon source, not a chemical carbon source, that can be used to fabricate the carbon microsphere support. This concept opens a new avenue for recycling and boosts the value of abundant waste biomass in nature.